No matter which Android device we get, as soon as it boots up we immediately jump into the hidden Developer options and speed up the animations. This will make the entire phone feel so much more responsive and snappy. Here’s how you do it:

Jump into your Settings app
Scroll down to the bottom and select About phone
Scroll to the bottom and press Build number 7 times
Press back button and select new Developer options at the bottom of Settings
Find window animation scale, transition animation scale, animator duration scale and select .5x for each"

I have since disabled the developer's option but it still will not recognise any bt devices..

Are you absolutely positive that Bluetooth was working before you changed the animation speed settings? Did you accidentally change something else in the developer settings? I have changed the speed settings back and forth many times on this phone, as well as on many other phones, and never had an issue with Bluetooth, or anything else as a result.

It's a wonky Bluetooth for sure. It should be working. Keep rescanning for devices, restart your car, etc while searching. It should finally catch up. There is no relationship between animation speeds and Bluetooth. I don't see anything in my dev options that would not let Bluetooth turn on. It took me a week to get it to sync to my Chrysler UConnect sysyem